Capsules and machines that operate on the aforementioned principle have been in existence for several decades.
Patents U.S. Pat. No. 2,899,886, U.S. Pat. No. 2,968,560, U.S. Pat. No. 3,403,617 and U.S. Pat. No. 3,607,297 describe devices in which the capsule is initially pierced at several points, then has pressurized water passed through it.
The capsule described in patent CH 605 293 or in patent EP 0 242 556 B1 comprises a membrane in its lower part. Water under pressure is initially introduced into the upper part of the capsule, causing the capsule to swell, mainly in the region of the membrane. Beyond a certain pressure, the membrane tears thereby allowing a water-coffeee mixture to flow out.
Other capsules equipped with membranes are described in the following patent documents: EP 0 468 079 A, EP 0 806 373 A, EP 0 554 469 A.
The present invention seeks to avoid the use of capsules made of a material that can be deformed on contact with hot water. This is because that type of material can cause malfunctioning in certain devices.
The subject of the invention is therefore a device for preparing a drink extracted from a capsule comprising a capsule support and a capsule cage inside which there are at least a water inlet and capsule-piercing means, characterized in that said cage is sized in such a way as to deform, at least partially, any capsule, made of a material that can be deformed upon contact with hot water, which is placed in the cage, so that the capsule is retained in the cage following its contact with hot water.
According to a first embodiment of the invention, the internal wall of the cage comprises a recess in which is housed a deformable element the coefficient of rigidity of which is greater than the coefficient of rigidity of the material of which the capsule is made.
The recess may have the form of an annular groove or of one or several holes.
According to another embodiment of the invention, the internal wall of the cage comprises pivoting elements of the vane type which are designed to be completely housed in the wall of the cage if the coefficient of rigidity of the capsule exceeds a set value and, if not, to emerge at least partially from said wall.
According to another embodiment of the invention, the internal wall of the cage comprises a relief of the barbed hook type.
Finally, the internal wall of the cage may be in the form of a bell and has an internal volume greater than the volume of the capsules.